The present invention relates to image recording apparatus suitable for automatically recording traffic signal violations, such as failure of a vehicle to stop at a red traffic control signal at an intersection, a crossing for pedestrians or other location where traffic signals are used to control vehicular traffic.
Prior art recording devices for this purpose incorporate automatic camera systems which are triggered when a vehicle fails to stop after a traffic light turns red. A typical device may be triggered by a road sensor such as an inductive loop or loops installed below the road surface which senses the presence of a motor vehicle after it crosses a marked stop line associated with the traffic signal. The road sensor may alternatively be of the piezo type, and may be triggered when a vehicle touches the sensor installed within the road surface. Piezo type sensors are used when recording of accurate vehicle speed is required in addition to traffic light violation.
The usual method of recording images is by photographic means using 35 mm film. Two images (photographs) are recorded of each violation. One image is recorded as the vehicle proceeds over the stop line associated with the traffic signal and a further image is recorded approximately one half second later (or more depending upon the size of the intersection) to establish movement of the vehicle. In each photograph a data inset is included showing the date, time of day and the time (in seconds) that traffic lights had been red when the violation took place. Note that if only one photograph was taken, there would be no way of determining whether the vehicle actually proceeded through the intersection, turned left or right or stopped just over the stop line.
A disadvantage of prior art recording devices is that the position of the vehicle relative to the stop line when the lights turned red, is not known and can only be crudely estimated from the distance travelled by the vehicle in the two photographs taken, plus the red light time shown on the data inset in each photograph. In the case of a defended matter in Court the prosecution must prove that the lights were red before the vehicle concerned proceeded across the stop line. To ensure that this does in fact happen in each case, the cameras are set so that at least one half second of red light time elapses before the road sensors are enabled. As a result of this requirement many vehicles actually proceed through the red light without being detected during the first half second of red light time.
Bearing in mind that the distance covered by a vehicle in the first half second of red signal is dependant on vehicle speed, it is apparent that only the worst cases of red light traffic infringements ever get captured by the camera. There are considerably more red light traffic infringements occurring during the first half second of red signal which could be detected.
An object of the present invention is to provide image recording apparatus which alleviates the disadvantages of the prior art.